In oil or gas operations, such as, for example, the fracturing or gravel packing of a subterranean wellbore, one or more plug valves may be used to control the flow of fracturing and/or gravel-packing fluids. A plug valve generally includes a valve body defining a pair of fluid passages that intersect an internal cavity formed in the valve body. The internal cavity of the valve body accommodates an insert and a plug. The plug extends within and engages the insert, which insert, in turn, extends within and engages the valve body. The plug and the insert include fluid passages that are adapted to be substantially aligned with the respective fluid passages of the valve body. Moreover, the plug is adapted to rotate relative to the insert and the valve body to selectively prevent or allow the flow of a fracturing or gravel-packing fluid through the respective fluid passages of the valve body, the insert, and the plug.
The extreme pressures, temperatures, and flow rates encountered by the plug valve during oil or gas operations often cause thermal expansion of the plug valve. Moreover, axial forces such as, for example, hydraulic lift, are imparted to the insert and/or the plug during operation of the plug valve. In some cases, due to the thermal expansion of the plug valve, the plug valve is unable to maintain the substantial alignment between the respective fluid passages of the plug, the insert, and the valve body. As a result, the axial forces imparted to the plug and/or the insert during operation of the plug valve urge the fluid passages of the plug, the insert, and the valve body out of substantial alignment with one another. The resulting misalignment causes wear, erosion, or complete wash-out of the plug, the insert, and/or the valve body.
Therefore, what is needed is an apparatus or method to address one or more of the foregoing issues, and/or one or more other issues.